This invention relates to a technology which sets up access restriction information on a storage device.
Utilization of computer systems has been advanced in many fields such as commerce and entertainment, and various data such as texts, sounds, still pictures, and motion pictures has been computerized. As a result of that, there is a tendency that the amount of data which is stored on a storage device of a computer, represented by a disk array device increases rapidly, and a storage device has been changed to one of large-scale. Also, in the field of highly public financial institutions and electronic commerce etc., which depends upon computer systems, it is required not only to have high capacity and high performance but also to continue operation of a storage device for 24 hours, and for 365 days. In case of unavoidably stopping it because of a system maintenance work and so on, it is necessary to shorten down time as much as possible.
As an example of the system maintenance work, cited is a case of introducing a new storage device into a computer system. In case that the storage device (new storage device) to be introduced is connected to a host computer, and data on an existing storage device (old storage device) is relocated to the new storage device, since there is a necessity that a connection of the host computer and the old storage device is cut off once, and data is copied from the old storage device to the new storage device, the operation of the computer system is stopped. In order to copy massive data from the large-scale old storage device, there is a necessity to stop the system for a long time.
In pages 18 to 20, FIGS. 1 and 3 of Japanese Patent Publication No. H10-508967 of Japanese translation of PCT international patent application (hereinafter, referred to as Patent Document 1), disclosed is a method of shortening down time of a system at the time of data transfer work, by carrying out a data transfer process during a period of system operation. In this method, the host computer and the new storage device are connected, and furthermore, the new storage device and the old storage device are connected. The new storage device copies data on the old storage device to its own storage area. The new storage device accepts an access request from the host computer to the data even in the copy operation, and if data of a destination of the access exists in its own storage area, the data is accessed. In case that it does not exist in its own storage area, firstly, the data is copied from the old storage device, and then, it is accessed. In this operation with the new storage device, it becomes possible to continuously operate the system even in a data transfer working state.